What is there to like about this movie? Well, the plot is pretty good, even though I'd have much more trouble suspending my disbelief if it would not have been French. In the wake of all the ruckus in France, this movie feels pretty realistic as a social commentary.
The stunts(Parkour) are amazing. Smooth, fluid motion and crisp, no-bullshit camera-work makes it a real treat to the eye. The fighting scenes are cool too, and they at least partially real(for unreal, watch Hard Target or any other Van Damme movie. For real, watch Heat) and not as repetitive and drawn-out as the usual ones.
The whole ghetto atmosphere works really well. Concrete and poverty works fine as scenery. Dialouge seemed good too from what I got from the subtitles.
What's there to dislike? Well, character development is the same-old. Two different guys team up and saves the day, overcome their differences and live happily ever after. It has been done before, but at least it's done well here.
The music is consistent and fitting, so that's more of a matter of taste.
Otherwise, the movie is pretty much solid. Minor flaws, but on the whole a treat from the moment it starts to the end. Not something you add to the DVD collection, maybe, but certainly worthwhile. -7/10